Quote:
Originally Posted by jamesqf
Certainly it's germane. It is a working demonstration (and of the most extreme case) of the fact that you can extract energy from absolute wind, even in instances where "common sense" suggests you shouldn't be able to. Thus a car with a turbine generator (and it's irrelevant whether it's on the front, back, or in the middle) could in principle extract energy in excess of the drag it adds, as long as you're driving in windy conditions.
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I went into my fluid mechanics text.I was wrong about the numbers I shared.The theoretical maximum efficiency of a wind turbine is 59.3%.
The text reported that in actual practice,the efficiency rarely exceeds 40%.
Wind is free,so there's an engineering 'disconnect' with respect to 'fuel cost',and fuel economy'.
When the automobile's engine must create all the 'wind energy' for the turbine to extract it's portion ,we run smack dab into the 2nd Law of Thermo.
There are sail effects associated with automobiles,given certain relative wind spectra.It's been known about since around the 1920s.But it occurs at very low driving speeds.Lower than motorists would put up with.And we have no control over wind speed and direction.
And as far as I know,contemporary wind turbines simply orient their turbine blades into the wind.
Reaction turbines have exotic,streamlined stator turning vanes to guide the flow onto the turbine blades.
The larger the turbine,the more efficient,due to the relative leakage proportion around the blades.A small,ducted,'internal' turbo-generator would suffer this inefficiency.
If you've got some peer-reviewed scientific paper which illustrates how we go from 59.3%,to 100+% efficiency with a turbine electric generator 'd love to see that.
